TODAY | January 07, 2014
>>> break-in. the theft of government documents from an fbi office just outside of philadelphia. more than 40 years later, the burglars are coming forward for the first time in a new book and documentary. and they're speaking out to nbc news. here's our national investigative correspondent michael isikoff .
>> a mystery for 43 years. the night the nation was gripped by the fight of the century , ali frazier at madison square garden . burglars broke into this fbi office outside philadelphia in march 1971 and stole 1,000 secret documents . the culprits never found.
>> we did it. somebody had to do it.
>> and now a surprise confession.
>> we just took all the files. we didn't sort anything.
>> reporter: in an exclusive nbc news interview, the burglars, antivietnam war activists admitted they committed the crime to expose what they believed were illegal activities by the fbi .
>> massive illegal surveillance and intimidation.
>> bonny cased the office posing as a college student leaving no fingerprints.
>> i never took my gloves off.
>> her husband, john rames, a retired religion professor drove the get away car.
>> i was sitting by myself in the station wagon and getting very, very scared.
>> the documents exposed fbi efforts to spread paranoia among left wing groups and cointelpro, a program started earlier by j. edgar hoover . betty was the first reporter to get the documents in her mailbox. she's now written "the burglary" and how it led to new rules forbidding political snooping.
>> it's safe to say that the fbi was never the same again.
>> the statute of limitations has long expired, but patrick kelly , the ex-agent who investigated the case back then says the theft remains inexcusable.
>> they're rationalizing a criminal act . i don't believe such people have a right to take upon themselves and make decisions.
>> but they're proud of what they did and have a message they see as the modern day counterpart edward snowden.
>> from one whistleblower to another whistleblower, hey.
>> nbc news, washington.